The present invention relates to pupillary measurements and, more particularly, to a system, method and device for measuring pupillary distance that can take into consideration relevant position of the individual's nose-bridge through a calibration frame, and so facilitating online purchases as well as in-store dispensing of prescription frames.
Traditionally, measuring pupillary distance required an individual to utilize the services of an optician using a ruler or specialized equipment, usually by visiting an optical store, to obtain such measurements. Such measurements include pupillary distances, wherein the pupillary distances are the horizontal distance between each eye-pupil and the center of the frame nose-bridge (always necessary to make eyeglasses).
In-store measurements were the norm because even a small pupillary distance error can make prescription eyeglasses exhibit prismatic behavior, causing squinting, headaches, and dizziness. The importance of aligning an optical lens with the individual's eye pupil is one of the key factors for making prescription eyeglasses successfully.
Recently, methods of measuring pupillary distance have been developed so the individual need not employ the services of an optician—i.e., remote methods. One popular method consists on taking a picture of the individual while placing the back-side of a credit card, a CD/DVD or an object of a commonly known length on his/her chin in order to be able to obtain the scale of the picture and calculate the inter-pupillary distance from the picture. However, this method is not suitable for an individual with an asymmetrical face, as the actual pupillary distances from the nose to their corresponding right and left eyes may differ from the value obtained from a single inter-pupillary measurement.
Another popular remote method consists on having the individual taking his/her own measurements in front of a mirror using a ruler; either with or without the assistance of another person. Since even experienced opticians have difficulty taking their own measurement in a mirror, this method is prone to pupillary measurement error(s) and its associated effects mentioned above.
Yet, another remote method consists on taking a picture of the individual's face; then analyzing the image with the assumption that all human iris have the same diameter-size in order to establish a picture scale and an inter-pupillary distance from the picture; since the size of the human iris varies from person to person with a range of 10.2 to 13 mm, this method is prone to pupillary measurement errors and neither suitable for an individual with an asymmetrical face.
As can be seen, there is a need for a system for measuring pupillary distances that can take into account the actual position of the individual's nose-bridge through employing a calibration frame that can be mass produced for universal application, and so facilitating online purchases as well as in-store dispensing of prescription frames.